ANIMAL FLUIDS AND TISSUES. 429 



bases called ptomaines or cadaveric alkaloids, substances which have 

 been spoken of in Chapter 50. The decomposition of organic matter 

 may be prevented under conditions which have been mentioned here- 

 tofore in connection with putrefaction. 



53. ANIMAL FLUIDS AND TISSUES. 



Constituents of the animal body. The animal body consists 

 mainly of three kinds of matter, viz., water, organic and inorganic 

 matter. It contains of water about 70 per cent., of organic matter 

 25 per cent., and of inorganic matter about 5 per cent. The water 

 may be determined by drying a weighed quantity in an air-bath at a 

 temperature of 100 to 105 C. (212 to 221 F.); the organic matter 

 is estimated by burning the dried substance, and the inorganic matter 

 (ash) by weighing the residue. Some of the elements which are left 

 in the inorganic residue have, however, been actually constituents of 

 organic compounds ; iron, for instance, which is left in the ash, has 

 been chiefly a constituent of haemoglobin ; sulphur, left as a sulphate, 

 may have been a constituent of albumin, etc. 



The relative quantities of the three constituents in some of the 

 animal fluids and tissues is shown in the following table : 



Organic and Inorganic resi- 

 volatiie matter. due (ash). 



the chemical changes which food suffers during digestion. 518. Mention the 

 principal fluids which are secreted by various organs of the animal body in 

 order to facilitate or cause digestion. 519. What are the waste products of 

 animal life, and through which channels are they eliminated ? 520. What is 

 the final result of the decomposition of dead plants or animals ? 



i The metals in combination with the biliary acids not included. 



